Most of my projects are on GitHub. I'm currently with the Portland Trail Blazers.

One Little Pointer

Every Objective-C object must begin with an isa pointer, otherwise the runtime won’t know how to work with it. Everything about a particular object’s type is wrapped up in that one little pointer. The remainder of an object is basically just a big blob and as far as the runtime is concerned, it is irrelevant. It’s up to the individual classes to give that blob meaning.

Mike Ash